The US House of Representatives has pushed through a financial amendment preventing the National Security Agency (NSA) from using government funds "to conduct warrantless searches for the communications of United States persons".
Tacked on to the Fiscal Year 2015 Department of Defense Appropriations Act, the amendment follows pressure from Representatives since ex-NSA contractor Edward Snowden revealed the extent to which US law enforcement agencies secretly survey and even store data from US, and global, citizens without warrant or legal approval.
Snowden's leaked documents suggested that such acts are routinely carried out under a scheme named "Prism".
For his revelations, Snowden is now a wanted criminal in the eyes of the US authorities.
The searches in question that are losing funding include emails, internet browsing history and online chat history.
Government agencies can currently search this information without applying to a court for a warrant. As well as cutting off funding, the amendment will also prevent organisations, such as the NSA and CIA, from demanding so-called 'back door' access to new online services and products in the future, as they seem to have previously required from companies such as Yahoo and Microsoft.
The amendment still needs to pass through the Senate, the upper house, as well as the House of Representatives.
The amendment still seems to allow surveillance "for emergency situations", which can come about after "a reasonable belief that the life or safety of...[a] United States person is threatened and the information is sought for the purpose of assisting that person".
It is left to interpretation just what constitutes "emergency" in a global landscape of almost constant terror alerts.